Thermostatic switch plug



May 10, 1932. WALDER I 1,857,173

THERMOSTATIC SWITCH PLUG Filed March 25, 1928 .mfl.

24; 7 MM g A? 1 T'I'ORNEY.

. Patented May 10, 1932 UNITED STATES EMIL WALDER, OF PHILADELPHIA, PENNSYLVANIA THER-MOSTATIC SWITCH PLUG Application filed March 23, 1928. Serial No. 264,057.

The object of this invention is to devise a novel and simplified construction of a thermostatically controlledelectrical plug which can be used with either alternating or direct current.

In the electrical switch plugs which are thermostatically controlled as heretofore placed on the market they have been adapted for use only with alternating current and if attached to an electrical appliance using direct current they soon become destroyed.

In my prior application Serial No. 144,435 filed October 27th, 1926, I have described and broadly claimed a novel thermostatically l5 controlled electric circuit wherein a plurality of electromagnets are employed which cooperate with a switch which is in circuit with manually adjustable contacts which are thermostatically controlled.

of electromagnets which are arranged side by side instead of being opposed to each other as'in my prior application aforesaid, and an armature common to said electromagnets is controlled by them to eflect the opening and closing of an electric circuit. In conjunction with these magnets I employ manually adjustable contacts which cooperate with a bimetallic thermostat which is electrically connected with a terminal of the plug.

With the above in view and with other objects in view as will hereinafter more clearly appear, my invention comprehends a novel thermostatic switch plug adapted for use with either alternating or direct current.

It further comprehends a novel thermostatic switch plug wherein a pair of electromagnets are arranged side by side and cooperate with a common armature which is pivotally supported and forms a switch to effect the opening and closing of the circuit. A pair of manually adjustable contacts are controlled by a thermostat in electrical connection with a terminal of the plug to effect the, energization of one or the other of said .electromagnets.

\Vhen the circuit is closedthe circuit is shunted from the electromagnets to a switch.

The contacts are constructed in such a manner that one acts in advance of the other In my present invention I employ a pair and each contact is effective to control its respective electromagnet.

It further comprehends a novel thermostatic switch plug wherein a thermostatic 'break is employed comprising a thermostatically controlled main and shunt circuit, one of said shunt circuits controlling the opening of the main circuit and the other of said shunt circuits controlling the closing of the main circuit.

Other novel features of construction and advantage will hereinafter clearly appear in the detailed description and the appended claims.

For the purpose of illustrating the inven- 95 tion, I have shown in the accompanying drawings a typical embodiment of it, which, in practice, will give reliable and satisfactory results. It is, however, to be understood that this embodiment is typical only and that the various instrumentalities of which my invention consists can be variously arranged and organized, and the invention is not limited to the precise arrangement and organization of these instrumenta'lities as herein set forth.

Figure 1 is a top plan view of one section of a thermostatic switch plug embodying my invention showing the circuit as being open and with one of the casing sections removed for the sake of clearness of illustration.

Figure 2 is a plan view similar to Figure 1 but showing the circuit closed.

Figure 3 is a top plan view of the manually controlled contact member on an enlarged 35 scale and in detached position.

Figure 4 is a section on line 44 of Figure 2.

Figure 5 is a ure 1.

Figure 6 is awiring diagram.

Figure 7 is a plan View of a heat conducting element.

Similar numerals of reference indicate corresponding parts.

Referring to the drawings 1 designates the sectional body portion of a thermostatic switch plug embodying my invention. It will be understood that the plug is made in two sections, one of which 200 section on line 55 of Fig preferably carries all of the electrical parts. The plug has, secured to it the terminals or bindin posts 2 and 3 to which are connected 1n the usual manner the electrical conductors.

The terminal 2 secures to a casing section one end of an off-set strip'4 which is electrically connected with a terminal socket 5 by means of a screw 6, which latter alsoservestohetain the terminal socket 5 in fixed position on the casing section 1 of the plug. The other terminal socket 7 is secured to the casing section 1 by means of a fastening device 8 which is in electrical connection with a conducting member 9. This conducting member 9 is provided with an aperture 10 (Fig. 7) through which the fastenin device 8 passes and the conducting mem er is secured to the casing section 1 by means of fastening devices 11. The conducting member 9 is provided with an upwardly extend ing flange 12 to which is riveted one end of a bi-metallic strip 13.

It will thus be seen that the terminal socket 7, which is preferably the pilot terminal, is seated directly upon the conducting strip 9 to derive heat therefrom, and the thermostatic strip 13 extends towards the rear end of the plug in close proximity to such terminal socket 7 substantially throughout its length. The thermostatic strip 13, at its rear end, has riveted to it one end of a steel strip 14, the opposite end of which is provided with a contact 15 (Fig. 5).

The rivet 16, which secures the strip 14 to the bi-metallic strip 13, also secures to the strip 13 one end of a spring 17, the free end of which is provided with a contact 18.

19 designates a manually adjustable contact carrying member WlllCh is preferably made of insulating material; The member 19 has set into its bottom face (Fig. 5) a metallic plate 20 which is provided with a rounded or cam face 21 adapted to engage the lower contact 15. The contact carry ing member 19 has set into its top face (Fig. 5) a metallic plate 22 which is rounded or provided with a cam face 23 adapted to make contact with the spring carried contact 18.

The manually adjustable contact carrying member 19 is retained in position by means of,

a screw 24 which passes through an insulating sleeve 25 which extends from the upper contact carrying plate 22 through the lower conducting member 27. This screw 24 is in threaded engagement with a conducting plate 28 (Fig. 5) which is set into the casing section 1 and fixed therein in any desired manner.

4 The conducting member 27 is secured to a strip of insulating material 29 (Fig. 2) by means of a fastening device 30 in such a manne r that the conducting member 27 is not electrically connected with the conducting plate The terminal 3 is electrically connected with an arm 31 which is adapted to be received in the bifurcated end 32 of an armature 33 which forms a switch and which is pivotally mounted on a screw 34 which is in threaded and electrical engagement with the conducting plate 28. The armature 33 is common to two electromagnets 35 and 36, respectively, which are retained in position by the off-set conducting strip 4 which latter is insulated from the electromagnets by meims of the insulation on the wire of the (301 s.

The armature 33 is provided with the upwardly extending flanges 37 and 38 which cooperate with their respective electromagnets. A binding post 39 is inelectrical connection with the conducting plate 28.

The bi-metallic thermostatic strip 13 has the electromagnet 36 electrically connected with it by means of the line 40. At its opposite end, the winding of the electroma et 36 is connected. by the line 41 (Fig. 6) w1th the binding post 39 which, as before explained, is in electrical connection with the conducting plate 28. The winding of the electromagnet 35 is connected at one end by the line 42 with the terminal post 3 and by line 43 with the fastening device 30 which is electrically connected by the conducting member 27 with the lower contact 21.

A washer 44 is preferably employed between the head of the screw 24 and the upper contact carrying plate 22.

Referring now more articularly to the wiring diagram seen in igure 6, 45 designates a source of electric supply which is in electrical connection by means of the conductors 46 and 47 with'the terminals 2 and 3 respectively.

In Figure 1 the switch is shown in its open position at which time no current is asslng to the electrical appliance to which t e plug is connected. Assuming now that the thermostatic blade 13 assumes a position in which the upper contact 18 is in contact with the contact 23, and the lower contact 15 is in con tact with the contact 21, the circuit is closed so that current now flows from the binding post 3 through line 42, electromagnet 35, line 43, conducting strip 27, lower stationary contact 21, contact 15, bi-metallic blade 13, socket 7, electrical appliance to which the plug is connected, terminal socket 5, conducting strip 4 and binding post 2, thus energizing the electromagnet 35.

This energization-of the electromagnet 35 causes the switch 33 to move from the position seen in Figure 1 to that seen in Figure 2. The upper spring contact 18 is now in contact with the upper stationary contact 23 and the lower contact 15 is in contact with the lower stationary contact 21. The switch 33 is in The current now passes to the binding post 3, through switch 33, screw 34, conducting plate 28, screw 24, upper stationary contact 23, spring contact 18, thermostat blade 13, terminal socket 7, the electrical appliance,

'terminal socket 5 and to the binding post 2.

The current is thus shunted from the electromagnets when the circuit is closed through the electrical appliance. The circuit is also closed through the electromagnet 35, but due to there being less resistance in the main or workingcircuit the electromagnet 35 is not at this time energized.

Assuming now that the thermostatic blade 13 due to its temperature has moved into such position that contact15 does not contact with stationary contact 21 and contact 18 does not contact with stationary contact 23, the current is shunted through the electromagnet 36 by switch 33 conducting plate 28, binding post 39, line 41, and line 40 to thermostatic blade 13. This causes the electromagnet 36 to be energized thereby moving the switch 33 into the position seen in Figure 1,

. so that the main or working circuit is opened.

As soon as the switch 33 opens, the circuit is broken through the electromagnet 35, thus deenergizing such electromagnet.

The thermostatic blade on cooling returns to its initial position and the cycle of operation hereinbefore. described is repeated.

The upper contact 23 is slightly longer than the lower contact 21 as will be clear from Figure 5.

Having thus described my invention what I claim as new and desire to secure by LettersPatent, is

1. A thermostatic switch plug, having a casing carrying the working parts, sockets on said casing adapted to receive the prongs of a conventional electrical heating appliance, a binding post, a conducting plate, an armature forming a switch electrically connected with said plate and effective to open and close the circuit through said binding post, a pair of electromagnets controlling said armature and arranged side by side, a pair of manually adjustable contacts, one of said electromagnets having its winding connected with said binding post and electrically connected with one of said contacts, a bimetallicthermostatic element deriving heat from one of said sockets 2nd a pair of contacts carried by said element and cooperating witlrsaid manually adjustable contact,

the other of said electromagnets having its winding electrically connected with said element and with said conducting plate.

2. A thermostatic switch plug, having a casing carrying the working parts, sockets on said casing adapted to receive the prongs of a conventional electrical heating appliance, a binding post, a conducting plate, an armature forming a switch electrically connected with said plate and etfective to open and close the circuit through said binding post, a pair of electromagnets controlling said armature and arranged side by side, a pair of manually adjustable contacts, one of which is longer than the other, one of said electro-magnets having its winding connected with said binding post and electrically connected with one of said contacts, a bimetallic thermostatic element deriving heat from one of said sockets, and a pair of contacts carried by said element and cooperating with said manually adjustable contact, the other of said electro-magnets having its winding electrically connected with said element and with said conducting plate.

3. A thermostatic switch plug, having a casing carrying the working parts, sockets on said casing adapted to receive the prongs of a conventional electrical heating appliance, a binding post, a conducting plate, an armature forming a switch electrically connected with said plate and etfective to open and close the circuit through said binding post, a pair of electromagnets controlling said armature and arranged side by side, a pair of manually adjustable contacts insulated from each other and simultaneously adjustable, one of said electro-magnets having its winding connected with said bindin post and electrically connected with one 0 said contacts, a bimetallic thermostatic element deriving heat from one of said sockets, and a pair of contacts carried by said element and cooperating with said manually adjustable contact, the other of said electromagnets having its winding electrically connected with said element and with said conducting plate.

4. A thermostatic switch plug, having a casing carrying the working parts, sockets on said casing adapted to receive the prongs of .a conventional electrical heating appliance,

a binding post, a conducting plate, an armature forming a switch electrically connected with said-plate and elfective to open and close the circuit through said binding post, a pair of electro-magnets controlling said armature and arranged side by side, a pair of manually adjustable contacts, one of said element contacts being fixed to it, and the other element contact being resiliently carried by such element, one of said electro-magnets having its winding connected with said binding post and electrically connected with one of said contacts, a bimetallic thermostatic element deriving heat from one of said sockets, and a pair of contacts carried by said eleance, a binding post, a conducting plate, an armature forming a switch electrically connected with said plate and efi'ective to open and close the circuit through said binding 5 post, a pair of electro-magnets controlling said armature, disposed side by side, a pair of manually adjustable contacts, one of said electro-magnets having its winding connected with said binding post and electrically connected with one of said contacts, a bimetallicthermostatic element deriving heat from one of said sockets, and a pair of contacts carried by said element and cooperating with said manually adjustable contact, one of said element contacts being longer than the other, the other of said electro-magnets having its winding, electrically connected with said element and with said conducting plate. A 6. In a thermostatic plug, a casing, plug terminals and binding posts at opposite ends thereof, and thermostatically controlled mechanism between said terminals and binding-posts and enclosed in said casing having an externally operable controlling member disposed in substantial parallelism to the planes of said terminals.

7. In ath'ermostatic plug, a casing, plug terminals and binding posts at opposite ends thereof, thermostatically controlled mechanism therebetween including a plurality of shunt coils disposed in parallelism to one another, a bridging conductor between one bindin post and one terminal extending over said coils, and: controlling mechanism between said coils and'the opposite side of the casing. 8. In a thermostatic plug, acasing, plug terminals and binding posts at opposite ends thereof, and'thermostatic controlling mecha- 40 nism therein comprising a plurality of shunt coils, a combined armature and contact member between said coils and the opposite side of the casing, and cooperating thermostaticallyand manually controlled mechanism between said member and the opposite side of the casing.

a EMIL WALDER. 

